Method of preparing aromatic vinyl compound-vinyl cyanide compound polymer and apparatus for preparing the same

ABSTRACT

The present invention relates to a method of preparing an aromatic vinyl compound-vinyl cyanide compound polymer including a step of separating volatile components from a polymerization product containing an aromatic vinyl compound-vinyl cyanide compound polymer, a residual aromatic vinyl monomer, a residual vinyl cyanide monomer, and an organic solvent using a volatilization tank, and a step of condensing the separated volatile components using a condenser, wherein an organic solvent or an aromatic vinyl monomer is sprayed onto the volatile components being transferred to the condenser. Volatile components may be fully condensed in a condenser, thereby significantly reducing the amount of volatile components discharged to the outside without being condensed. Therefore, wastewater treatment costs consumed in treating the volatile components may be reduced, and the amount of vinyl cyanide monomers harmful to the human body discharged into the atmosphere may be significantly reduced.

CROSS-REFERENCE TO RELATED APPLICATIONS

The application is a National Phase of International Application No.:PCT/KR2019/009587 filed on Aug. 1, 2019, which claims priority to KoreanPatent Application No. 10-2018-0164399, filed on Dec. 18, 2018, andKorean Patent Application No. 10-2019-0072784, re-filed on Jun. 19,2019, based on the priority of the above patent, in the KoreanIntellectual Property Office, the disclosures of each of which areincorporated herein by reference.

Technical Field

The present invention relates to a method of preparing an aromatic vinylcompound-vinyl cyanide compound polymer and an apparatus for preparingthe same. More specifically, the present invention relates to a methodof preparing an aromatic vinyl compound-vinyl cyanide compound polymerincluding a step of separating volatile components from a polymerizationproduct containing an aromatic vinyl compound-vinyl cyanide compoundpolymer, a residual aromatic vinyl monomer, a residual vinyl cyanidemonomer, and an organic solvent using a volatilization tank; and a stepof condensing the separated volatile components using one condenser ortwo or more condensers connected in series, wherein the method includesa step of spraying an organic solvent onto the separated volatilecomponents being transferred from the volatilization tank to thecondenser; or a step of spraying an organic solvent or an aromatic vinylmonomer onto the volatile components not being condensed in a firstcondenser and being transferred to a second condenser when the two ormore condensers connected in series are used, and to an apparatus forpreparing the aromatic vinyl compound-vinyl cyanide compound polymer.According to the present invention, the amount of residual monomers andorganic solvents discharged may be reduced.

Background Art

In general, aromatic vinyl compound-vinyl cyanide compound polymers haveexcellent moldability, rigidity, and electrical properties, and thus arewidely used in various fields including office automation (OA) equipmentsuch as computers, printers, and copiers, home appliances such astelevisions and audio systems, electric and electronic components, andgeneral goods. In particular, aromatic vinyl compound-vinyl cyanidecompound polymers having improved heat resistance have been used in homeappliances, interior materials for housing and automobiles, and the likedue to the properties thereof of being not deformed at high temperature.

An aromatic vinyl compound-vinyl cyanide compound polymer is prepared byreacting an aromatic vinyl compound and a vinyl cyanide compound in anorganic solvent. As a result of the reaction, a polymerization productcontaining the aromatic vinyl compound-vinyl cyanide compound polymer isobtained. In this case, in addition to the final product, monomers andthe organic solvent remain in the polymerization product. Accordingly, aprocess for removing the residual monomers and organic solvent isessential.

According to a general procedure for preparing an aromatic vinylcompound-vinyl cyanide compound polymer, polymerization is performed ina reactor; a polymerization product discharged from the reactor afterpolymerization is transferred to a volatilization tank, and volatilecomponents such as residual monomers and organic solvents and anaromatic vinyl compound-vinyl cyanide compound polymer are separatedfrom each other in the volatilization tank; and condensation of theseparated volatile components is performed using a condenser, andpurification is performed to obtain a final product, an aromatic vinylcompound-vinyl cyanide compound polymer.

In general, a condensation system consisting of two or three condensersis used. In this case, condensation efficiency can be improved byincreasing the pressure in the condensers and lowering the temperatureof a refrigerant. However, due to installation limitations, there is alimit in lowering the temperature of a supplied refrigerant, resultingin discharge of uncondensed volatile components. In addition, when theamount of vinyl cyanide monomers having low boiling points is increased,condensation efficiency is lowered.

Uncondensed volatile components are discharged to the stream through awastewater treatment system or to the atmosphere. In this case,wastewater treatment incurs significant costs, and the dischargedvolatile components cause environmental pollution.

Therefore, to reduce the amount of volatile components discharged to theatmosphere or introduced into a wastewater treatment system whenpreparing an aromatic vinyl compound-vinyl cyanide compound polymer, amethod of preparing an aromatic vinyl compound-vinyl cyanide compoundpolymer using a condenser having improved condensation efficiency isrequired.

RELATED ART DOCUMENTS Patent Documents

-   (Patent Document 1) KR 10-2007-0073028 A

DISCLOSURE Technical Problem

Therefore, the present invention has been made in view of the aboveproblems, and it is one object of the present invention to provide amethod of preparing an aromatic vinyl compound-vinyl cyanide compoundpolymer including a step of separating volatile components from apolymerization product containing an aromatic vinyl compound-vinylcyanide compound polymer, a residual aromatic vinyl monomer, a residualvinyl cyanide monomer, and an organic solvent using a volatilizationtank; and a step of condensing the separated volatile components usingone condenser or two or more condensers connected in series, wherein themethod includes a step of spraying an organic solvent onto the separatedvolatile components being transferred from the volatilization tank tothe condenser; or a step of spraying an organic solvent or an aromaticvinyl monomer onto the volatile components not being condensed in afirst condenser and being transferred to a second condenser when the twoor more condensers connected in series are used, and an apparatus forpreparing the aromatic vinyl compound-vinyl cyanide compound polymer.According to the present invention, the amount of residual monomers andorganic solvents discharged may be reduced.

The above and other objects of the present invention can be achieved bythe present disclosure described below.

Technical Solution

In accordance with one aspect of the present invention, provided is amethod of preparing an aromatic vinyl compound-vinyl cyanide compoundpolymer including separating volatile components from a polymerizationproduct containing an aromatic vinyl compound-vinyl cyanide compoundpolymer, a residual aromatic vinyl monomer, a residual vinyl cyanidemonomer, and an organic solvent using a volatilization tank; andcondensing the separated volatile components using one condenser or twoor more condensers connected in series, wherein the method includesspraying an organic solvent onto the separated volatile components beingtransferred from the volatilization tank to the condenser; or sprayingan organic solvent or an aromatic vinyl monomer onto the volatilecomponents not being condensed in a first condenser and beingtransferred to a second condenser when the two or more condensersconnected in series are used.

In accordance with another aspect of the present invention, provided isan apparatus for preparing an aromatic vinyl compound-vinyl cyanidecompound polymer including a volatilization tank for separating volatilecomponents from a polymerization product containing an aromatic vinylcompound-vinyl cyanide compound polymer, a residual aromatic vinylmonomer, a residual vinyl cyanide monomer, and an organic solvent; andone condenser or two or more condensers connected in series forcondensing the separated volatile components, wherein the apparatusincludes a spray means for spraying an organic solvent into a transferpipe for transferring the separated volatile components to thecondenser; or a spray means for spraying an organic solvent or anaromatic vinyl monomer into a transfer pipe for transferring thevolatile components, which have not been condensed in a first condenser,to a second condenser, when the two or more condensers connected inseries are included.

Advantageous Effects

According to the present invention, when an aromatic vinylcompound-vinyl cyanide compound polymer is prepared, an organic solventor an aromatic vinyl monomer is sprayed onto volatile components beingtransferred to a first condenser or the volatile components not beingcondensed in the first condenser and being transferred to a secondcondenser without replacing equipment. Through this process, the contentof vinyl cyanide monomers having low boiling points contained in thevolatile components can be reduced, thereby improving condensationefficiency. Therefore, wastewater treatment costs consumed in treatinguncondensed volatile components can be reduced, and the amount ofvolatile components harmful to the human body discharged into theatmosphere can be significantly reduced.

DESCRIPTION OF DRAWINGS

FIG. 1 schematically illustrates a step of separating volatilecomponents from a polymerization product containing an aromatic vinylcompound-vinyl cyanide compound polymer, a residual aromatic vinylmonomer, and an organic solvent and condensing the separated volatilecomponents, according to the present invention.

FIG. 2 schematically illustrates a step of separating volatilecomponents from a polymerization product containing an aromatic vinylcompound-vinyl cyanide compound polymer, a residual aromatic vinylmonomer, and an organic solvent and condensing the separated volatilecomponents, according to the related art.

BEST MODE

Hereinafter, the method of preparing an aromatic vinyl compound-vinylcyanide compound polymer according to the present invention will bedescribed in detail.

When an aromatic vinyl compound-vinyl cyanide compound polymer isprepared, volatile components separated from a polymerization productare not fully condensed in a condensation process and are discharged tothe outside. In this case, wastewater treatment costs are incurred andenvironmental pollution is caused. To solve these problems, the presentinventors have made efforts, and as a result, confirmed that when anorganic solvent or a monomer is added to volatile components beingtransferred to a condenser, condensation efficiency is improved and theamount of volatile components discharged without being condensed isreduced. Based on these findings, the present inventors conductedadditional studies and completed the present invention.

The method of preparing an aromatic vinyl compound-vinyl cyanidecompound polymer according to the present invention is as follows.

The method of preparing an aromatic vinyl compound-vinyl cyanidecompound polymer according to the present invention includes a step ofseparating volatile components from a polymerization product containingan aromatic vinyl compound-vinyl cyanide compound polymer, a residualaromatic vinyl monomer, a residual vinyl cyanide monomer, and an organicsolvent using a volatilization tank; and a step of condensing theseparated volatile components using one condenser or two or morecondensers connected in series, wherein the method includes a step ofspraying an organic solvent onto the separated volatile components beingtransferred from the volatilization tank to the condenser; or a step ofspraying an organic solvent or an aromatic vinyl monomer onto thevolatile components not being condensed in a first condenser and beingtransferred to a second condenser when the two or more condensersconnected in series are used. According to the method of the presentinvention, condensation efficiency may be improved, and the amount ofvolatile components discharged may be significantly reduced.

In the present invention, the first and second condensers may be any twocondensers of two or more condensers connected in series, respectively.In this case, the first condenser may be the condenser of the firststage, and the second condenser may be the condenser of the secondstage.

For example, the method of preparing an aromatic vinyl compound-vinylcyanide compound polymer according to the present invention includes astep of separating volatile components from a polymerization productcontaining an aromatic vinyl compound-vinyl cyanide compound polymer, aresidual aromatic vinyl monomer, a residual vinyl cyanide monomer, andan organic solvent using a volatilization tank; and a step of condensingthe separated volatile components using two or more condensers connectedin series, wherein the method includes a step of spraying an organicsolvent onto volatile components being transferred to a first condenserafter being separated in the volatilization tank; or a step of sprayingan organic solvent or an aromatic vinyl monomer onto the volatilecomponents not being condensed in the first condenser and beingtransferred to a second condenser. According to the method of thepresent invention, condensation efficiency may be improved, therebyreducing the amount of the volatile components discharged.

For example, the method of preparing an aromatic vinyl compound-vinylcyanide compound polymer may include a step of spraying an organicsolvent onto volatile components being transferred to a first condenserafter being separated in the volatilization tank; and a step of sprayingan organic solvent or an aromatic vinyl monomer onto the volatilecomponents not being condensed in the first condenser and beingtransferred to a second condenser. In this case, condensation efficiencymay be improved, thereby significantly reducing the amount of thevolatile components discharged.

For example, the method may include a step of polymerizing the aromaticvinyl compound and the vinyl cyanide compound before the step ofseparating the volatile components.

For example, the aromatic vinyl compound-vinyl cyanide compound polymermay be prepared by polymerizing the aromatic vinyl compound and thevinyl cyanide compound in an organic solvent.

For example, when the polymerization reaction is performed, one or moreselected from the group consisting of initiators, molecular weightregulators, and emulsifiers may be included.

For example, the polymerization reaction may be bulk polymerization,solution polymerization, or emulsion polymerization, preferably bulkpolymerization or solution polymerization. In this case, the mechanicalproperties such as tensile strength and impact strength, heatresistance, and heat stability of the prepared aromatic vinylcompound-vinyl cyanide compound polymer may be excellent.

In the present invention, a reaction method for obtaining the aromaticvinyl compound-vinyl cyanide compound polymer is not particularlylimited, and general polymerization methods may be used.

For example, the step of separating the volatile components in thevolatilization tank may be performed at a temperature of 220 to 260° C.under a pressure of 35 Torr or less, preferably a temperature of 225 to255° C. under a pressure of 15 to 35 Torr. Within this range, thevolatile components may be effectively separated from the aromatic vinylcompound-vinyl cyanide compound polymer.

Volatilization tanks generally used in the art to which the presentinvention pertains may be used as the volatilization tank of the presentinvention without particular limitation.

For example, the separated volatile components may include 5 to 35% byweight of the vinyl cyanide compound, 45 to 80% by weight of thearomatic vinyl compound, and 5 to 50% by weight of the organic solvent.

As a specific example, the separated volatile components may include 5to 20% by weight of the vinyl cyanide compound, 45 to 59% by weight ofthe aromatic vinyl compound, and 25 to 45% by weight of the organicsolvent, or may include 15 to 35% by weight of the vinyl cyanidecompound, 60 to 80% by weight of the aromatic vinyl compound, and 5 to25% by weight of the organic solvent.

For example, the aromatic vinyl compound-vinyl cyanide compound polymerpassed through the volatilization tank may be transferred to apelletizer and cut therein. Then, cooling and drying are performed toobtain the aromatic vinyl compound-vinyl cyanide compound polymer in apellet form.

In the present invention, two or more condensers are preferablyconnected to each other in series, or two condensers may be connected toeach other in series. In this case, condensation efficiency may beimproved.

In the present invention, condensers commonly used in the art to whichthe present invention pertains may be used as the condensers of thepresent invention without particular limitation.

For example, in the step of spraying the organic solvent or the aromaticvinyl monomer onto the volatile components not being condensed in thefirst condenser and being transferred to the second condenser, theorganic solvent or the aromatic vinyl monomer may be sprayed at a flowrate of 10 to 220 kg/hr or 10 to 110 kg/hr, preferably 10 to 90 kg/hr,more preferably 10 to 40 kg/hr. In this case, the content of residualvinyl cyanide monomers having low boiling points contained in thevolatile components may be reduced, thereby improving condensationefficiency.

For example, in the step of spraying the organic solvent onto thevolatile components being transferred to the first condenser after beingseparated in the volatilization tank, the flow rate of the organicsolvent may be 10 to 100 kg/hr, preferably 20 to 90 kg/hr. In the stepof spraying the organic solvent or the aromatic vinyl monomer onto thevolatile components not being condensed in the first condenser and beingtransferred to the second condenser, the flow rate of the organicsolvent or the aromatic vinyl monomer may be 10 to 100 kg/hr, preferably15 to 90 kg/hr. In this case, condensation efficiency may be improved,thereby significantly reducing the amount of the volatile componentsdischarged.

For example, in the step of spraying the organic solvent onto thevolatile components being transferred to the first condenser after beingseparated in the volatilization tank, the organic solvent may be sprayedat a temperature of −10 to 40° C., preferably 0 to 30° C., morepreferably 15 to 25° C. Within this range, condensation efficiency maybe improved.

In the present invention, the temperature of the organic solvent sprayedto the first condenser is not particularly limited.

For example, in the step of spraying the organic solvent or the aromaticvinyl monomer onto the volatile components not being condensed in thefirst condenser and being transferred to the second condenser, theorganic solvent or the aromatic vinyl monomer may be sprayed at a flowrate of 10 to 200 kg/hr or 10 to 110 kg/hr, preferably 10 to 90 kg/hr,more preferably 10 to 40 kg/hr. In this case, the content of residualvinyl cyanide monomers having low boiling points contained in thevolatile components may be reduced, thereby improving condensationefficiency.

In the present invention, flow rates may be measured using a flow meteror calculated by a mass balance equation. According to the mass balanceequation, the flow rate of uncondensed volatile components may becalculated using an input, an output, and a recovered amount.

For example, in the step of spraying the organic solvent or the aromaticvinyl monomer onto the volatile components not being condensed in thefirst condenser and being transferred to the second condenser, theorganic solvent or the aromatic vinyl monomer may be sprayed at atemperature of −10 to 40° C., preferably 0 to 30° C., more preferably 15to 25° C. Within this range, condensation efficiency may be improved.

In the present invention, the temperature of the organic solvent or thearomatic vinyl monomer sprayed to the second condenser is notparticularly limited.

For example, condensation in the first condenser may be performed at arefrigerant temperature of 20 to 35° C. under an operating pressure of 3to 100 Torr, preferably at a refrigerant temperature of 25 to 33° C.under an operating pressure of 15 to 35 Torr, more preferably at arefrigerant temperature of 25 to 30° C. under an operating pressure of15 to 30 Torr. Within this range, condensation efficiency may beimproved.

In the present invention, the operating pressure refers to the internalpressure of the condenser formed when the condenser is operated.

For example, condensation in the second condenser may be performed at arefrigerant temperature of −3 to 4° C. under an operating pressure of 5to 50 Torr, preferably at a refrigerant temperature of −1 to 4° C. underan operating pressure of 7 to 25 Torr, more preferably at a refrigeranttemperature of 0 to 4° C. under an operating pressure of 10 to 20 Torr.Within this range, condensation efficiency may be improved.

For example, condensates condensed in the first and second condensersmay be recovered, purified, and reintroduced into a reactor. In thiscase, raw material costs may be reduced.

For example, the volatile components not condensed in the secondcondenser may be transferred to a vacuum unit, dissolved in acirculating fluid of a water-cooled pump, and discharged through awastewater treatment process. In this process, some of the volatilecomponents may be released into the atmosphere. According to the presentinvention, the amount of the volatile components released into theatmosphere may be significantly reduced, and environmental pollution maybe prevented.

For example, the organic solvent may include one or more selected fromthe group consisting of toluene, ethylbenzene, xylene,methylethylketone, and isobutylmethyl ketone. Preferably, the organicsolvent used in the polymerization reaction and the organic solvent tobe sprayed are the same. In this case, components having high boilingpoints may be added to the volatile components, and as a result, theratio of components having low boiling points, i.e., residual vinylcyanide monomers, contained in the volatile components may be reduced,thereby improving condensation efficiency.

For example, the aromatic vinyl compound may include one or moreselected from the group consisting of styrene, α-methyl styrene,p-methyl styrene, p-bromostyrene, p-chlorostyrene, and o-bromostyrene.In this case, the ratio of residual vinyl cyanide monomers having lowboiling points contained in the volatile components may be reduced,thereby improving condensation efficiency.

The apparatus for preparing the aromatic vinyl compound-vinyl cyanidecompound polymer according to the present invention includes avolatilization tank for separating volatile components from apolymerization product containing an aromatic vinyl compound-vinylcyanide compound polymer, a residual aromatic vinyl monomer, a residualvinyl cyanide monomer, and an organic solvent; and one condenser or twoor more condensers connected in series for condensing the separatedvolatile components, wherein the apparatus includes a spray means forspraying an organic solvent into a transfer pipe for transferring theseparated volatile components to the condenser; or a spray means forspraying an organic solvent or an aromatic vinyl monomer into a transferpipe for transferring the volatile components, which have not beencondensed in a first condenser, to a second condenser, when the two ormore condensers connected in series are included. According to thepresent invention, condensation efficiency may be improved, and theamount of volatile components released after condensation may benegligible.

In the present invention, means configured to be connected to thetransfer pipe and capable of spraying the organic solvent or thearomatic vinyl monomer into the transfer pipe may be used as the spraymeans of the present invention without particular limitation. Forexample, a spray pipe, a spray bottle, and the like may be used as thespray means, and the spray means may be provided with a spray nozzle.

For example, the apparatus for preparing an aromatic vinylcompound-vinyl cyanide compound polymer according to the presentinvention includes a volatilization tank for separating volatilecomponents from a polymerization product containing an aromatic vinylcompound-vinyl cyanide compound polymer, a residual aromatic vinylmonomer, a residual vinyl cyanide monomer, and an organic solvent; andtwo or more condensers connected in series for condensing the separatedvolatile components, wherein the apparatus includes a spray pipe forspraying an organic solvent into a transfer pipe for transferring theseparated volatile components to a first condenser; or a spray pipe forspraying an organic solvent or an aromatic vinyl monomer into a transferpipe for transferring the volatile components, which have not beencondensed in the first condenser, to a second condenser. In this case,condensation efficiency may be improved, and the amount of the volatilecomponents released after condensation may be negligible.

For example, the apparatus for preparing an aromatic vinylcompound-vinyl cyanide compound polymer may include a spray pipe forspraying an organic solvent into a transfer pipe for transferring theseparated volatile components to a first condenser; and a spray pipe forspraying an organic solvent or an aromatic vinyl monomer into a transferpipe for transferring the volatile components, which have not beencondensed in the first condenser, to a second condenser. In this case,condensation efficiency may be improved, and the amount of the volatilecomponents released after condensation in the second condenser may benegligible.

For example, the spray pipe may include a nozzle.

In the present invention, nozzles commonly used in the art to which thepresent invention pertains may be used as the nozzle of the presentinvention without particular limitation.

The volatilization tank and the condenser included in the apparatus forpreparing an aromatic vinyl compound-vinyl cyanide compound polymerfollow the above description, and thus description thereof will beomitted.

The method of preparing an aromatic vinyl compound-vinyl cyanidecompound polymer and the apparatus for preparing the same according tothe present invention will be described with reference to FIGS. 1 and 2.Embodiments of the present invention disclosed in the presentspecification and drawings are only provided to aid in understanding ofthe present invention, and the present invention is not limited to theembodiments. In addition, only means necessary for describing thepresent invention are described, and other obvious means for carryingout the method and apparatus are omitted in the drawings.

FIG. 1 schematically illustrates a volatilization tank (DV), a firstcondenser (1^(st) CN), a second condenser (2^(nd) CN), a vacuum unit, atransfer pipe, and a spray pipe, which are used in Examples 1 to 21according to the present invention, and shows the apparatus of thepresent invention including a volatilization tank for separatingvolatile components from a polymerization product containing an aromaticvinyl compound-vinyl cyanide compound polymer, a residual aromatic vinylmonomer, a residual vinyl cyanide monomer, and an organic solvent,wherein the apparatus includes a spray pipe for spraying an organicsolvent into a transfer pipe for transferring the separated volatilecomponents to a first condenser; or a spray pipe for spraying an organicsolvent or an aromatic vinyl monomer into a transfer pipe fortransferring the volatile components, which have not been condensed inthe first condenser, to a second condenser.

In addition, the volatile components not condensed in the secondcondenser may be transferred to a vacuum unit and dissolved in acirculating fluid of a water-cooled pump. Then, the dissolved volatilecomponents may be discharged to the outside through a wastewatertreatment process or to the atmosphere.

Although not shown in the drawing, condensates condensed in the firstand second condensers may be reintroduced into a reactor.

In addition, FIG. 2 schematically illustrates a volatilization tank(DV), a first condenser (1^(st) CN), a second condenser (2^(nd) CN), anda vacuum unit, which are used in Comparative Examples 1, 8, and 12.Referring to FIG. 2, in the volatilization tank, volatile components areseparated from a polymerization product containing an aromatic vinylcompound-vinyl cyanide compound polymer, a residual aromatic vinylmonomer, and an organic solvent. The separated volatile components arecondensed in the first and second condensers. In this case, the volatilecomponents not condensed in the second condenser are transferred to avacuum unit, compressed by a pump, and dissolved in a circulating fluidof a water-cooled pump. Then, the dissolved volatile components aredischarged to the outside through a wastewater treatment process or tothe atmosphere.

Although not shown in the drawing, condensates condensed in the firstand second condensers may be reintroduced into a reactor.

Hereinafter, the present invention will be described in more detail withreference to the following preferred examples. However, these examplesare provided for illustrative purposes only and should not be construedas limiting the scope and spirit of the present invention. In addition,it will be apparent to those skilled in the art that various changes andmodifications may be made without departing from the spirit and scope ofthe present invention, and such changes and modifications are alsowithin the scope of the appended claims.

EXAMPLES

Conditions for each step are shown in Tables 1 to 5 below.

Volatile Component Separation Step

-   -   Separation Conditions A: Separation was performed at a        temperature of 230° C. under a pressure of 20 Torr. In this        case, volatile components separated in a volatilization tank        included 55.8% by weight of a styrene monomer, 7.25% by weight        of an acrylonitrile monomer, and 37% by weight of toluene.    -   Separation Conditions B: Separation was performed at a        temperature of 250° C. under a pressure of 30 Torr. In this        case, volatile components separated in a volatilization tank        included 68.2% by weight of a styrene monomer, 23.7% by weight        of an acrylonitrile monomer, and 9.1% by weight of toluene.    -   Separation Conditions C: Separation was performed at a        temperature of 240° C. under a pressure of 20 Torr. In this        case, volatile components separated in a volatilization tank        included 62% by weight of a styrene monomer, 15% by weight of an        acrylonitrile monomer, and 23% by weight of toluene.

Condensation Step

-   -   Condensation Conditions A: In the first condenser, condensation        was performed at a refrigerant temperature of 30° C. under a        pressure of 20 Torr. In the second condenser, condensation was        performed at a refrigerant temperature of 2° C. under a pressure        of 10 Torr.    -   Condensation Conditions B: In the first condenser, condensation        was performed at a refrigerant temperature of 30° C. under a        pressure of 30 Torr. In the second condenser, condensation was        performed at a refrigerant temperature of 2° C. under a pressure        of 20 Torr.    -   Condensation Conditions C: In the first condenser, condensation        was performed at a refrigerant temperature of 25° C. under a        pressure of 15 Torr. In the second condenser, condensation was        performed at a refrigerant temperature of −1° C. under a        pressure of 10 Torr.    -   Spray substances: Toluene is represented by “1”; styrene is        represented by “2”; α-methyl styrene is represented by “3”;        acrylonitrile is represented by “4”; and methacrylonitrile is        represented by “5”.

Example 1

Volatile components were separated according to Separation Conditions A.Then, the separated volatile components were condensed in a firstcondenser according to Condensation Conditions A, and then uncondensedvolatile components were transferred to a second condenser and condensedtherein. At this time, toluene was sprayed at a flow rate of 45 kg/hronto the volatile components being transferred to the first condenserafter separation in the volatilization tank, and no spray was performedon the volatile components not being condensed in the first condenserand being transferred to the second condenser.

Example 2

Volatile components were separated according to Separation Conditions A.Then, the separated volatile components were condensed in a firstcondenser according to Condensation Conditions A, and then uncondensedvolatile components were transferred to a second condenser and condensedtherein. At this time, no spray was performed on the volatile componentsbeing transferred to the first condenser after separation in thevolatilization tank, and styrene was sprayed at a flow rate of 30 kg/hronto the volatile components not being condensed in the first condenserand being transferred to the second condenser.

Example 3

Volatile components were separated according to Separation Conditions A.Then, the separated volatile components were condensed in a firstcondenser according to Condensation Conditions A, and then uncondensedvolatile components were transferred to a second condenser and condensedtherein. At this time, no spray was performed on the volatile componentsbeing transferred to the first condenser after separation in thevolatilization tank, and α-methyl styrene was sprayed at a flow rate of30 kg/hr onto the volatile components not being condensed in the firstcondenser and being transferred to the second condenser.

Example 4

Volatile components were separated according to Separation Conditions A.Then, the separated volatile components were condensed in a firstcondenser according to Condensation Conditions A, and then uncondensedvolatile components were transferred to a second condenser and condensedtherein. At this time, no spray was performed on the volatile componentsbeing transferred to the first condenser after separation in thevolatilization tank, and toluene was sprayed at a flow rate of 80 kg/hronto the volatile components not being condensed in the first condenserand being transferred to the second condenser.

Example 5

Volatile components were separated according to Separation Conditions A.Then, the separated volatile components were condensed in a firstcondenser according to Condensation Conditions A, and then uncondensedvolatile components were transferred to a second condenser and condensedtherein. At this time, toluene was sprayed at a flow rate of 20 kg/hronto the volatile components being transferred to the first condenserafter separation in the volatilization tank, and styrene was sprayed ata flow rate of 15 kg/hr onto the volatile components not being condensedin the first condenser and being transferred to the second condenser.

Examples 6 to 21

According to separation conditions and condensation conditions shown inTables 1 to 3 below, volatile components were separated and condensed,and the spray substances were sprayed onto the volatile components.

Comparative Example 1

The same procedure as Example 1 was performed except that toluene wasnot sprayed onto the volatile components being transferred to the firstcondenser after separation in the volatilization tank.

Comparative Examples 2 to 16

According to separation conditions and condensation conditions shown inTables 4 and 5 below, volatile components were separated and condensed,and the spray substances were sprayed onto the volatile components.

Test Example

In Examples 1 to 21 and Comparative Examples 1 to 16, the flow rate ofthe volatile components not condensed in the second condenser anddischarged therefrom was measured using a flow meter installed betweenthe second condenser and the vacuum unit, and the results are shown inTables 1 to 5 below.

In addition, in Examples 1 to 14 and Comparative Examples 1 to 16, thevinyl cyanide monomer not condensed in the first condenser andtransferred to the second condenser was sampled from the pipe disposedbetween the first condenser and the second condenser, and the content ofthe sampled vinyl cyanide monomer was quantified by gas chromatography.The results are shown in Tables 1 to 5 below.

TABLE 1 Examples Classification 1 2 3 4 5 6 7 Separation conditions in AA A A A A A volatilization tank Condensation conditions in A A A A A A Acondenser Substance sprayed on volatile 1 — — — 1 1 1 components beingtransferred to the first condenser Flow rate of substance sprayed 45 — —— 20 20 30 on volatile components being transferred to the firstcondenser (kg/hr) Substance sprayed on volatile — 2 3 1 2 3 1 componentsbeing transferred to the second condenser Flow rate of substance sprayed— 30 30 80 15 15 30 on volatile components being transferred to thesecond condenser (kg/hr) Content of vinyl cyanide monomer 12.5 13.0 13.011.8 12.9 12.9 12.2 which is not condensed in the first condenser and istransferred to the second condenser (% by weight) Flow rate of volatilecomponents 0 0 0 0 0 0 0 discharged without being condensed in thesecond condenser (kg/hr)

TABLE 2 Examples Classification 8 9 10 11 12 13 14 Separation conditionsin B B B B B B B volatilization tank Condensation conditions in B B B BB B B condenser Substance sprayed on volatile — — — — 1 1 1 componentsbeing transferred to the first condenser Flow rate of substance sprayed30 — — — 10 10 10 on volatile components being transferred to the firstcondenser (kg/hr) Substance sprayed on volatile — 2 3 1 2 3 1 componentsbeing transferred to the second condenser Flow rate of substance sprayed— 10 12 14 10 10 10 on volatile components being transferred to thesecond condenser (kg/hr) Content of vinyl cyanide monomer 52.9 53.4 53.152.7 52.7 52.7 52.7 which is not condensed in the first condenser and istransferred to the second condenser (% by weight) Flow rate of volatilecomponents 0 0 0 0 0 0 0 discharged without being condensed in thesecond condenser (kg/hr)

TABLE 3 Examples Classification 15 16 17 18 19 20 21 Separationconditions in C C C C C C C volatilization tank Condensation conditionsin C C C C C C C condenser Substance sprayed on volatile 1 — — — 1 1 1components being transferred to the first condenser Flow rate ofsubstance sprayed 150 — — — 65 65 90 on volatile components beingtransferred to the first condenser (kg/hr) Substance sprayed on volatile— 2 3 1 2 3 1 components being transferred to the second condenser Flowrate of substance sprayed — 110 110 215 65 65 90 on volatile componentsbeing transferred to the second condenser (kg/hr) Content of vinylcyanide monomer 19.7 21.5 21.5 18.4 20.7 20.7 19.2 which is notcondensed in the first condenser and is transferred to the secondcondenser (% by weight) Flow rate of volatile components 0 0 0 0 0 0 0discharged without being condensed in the second condenser (kg/hr)

TABLE 4 Comparative Examples Classification 1 2 3 4 5 6 7 8 Separationconditions in A A A A A A A B volatilization tank Condensationconditions in A A A A A A A B condenser Substance sprayed on volatile —2 3 4 5 — — — components being transferred to the first condenser Flowrate of substance sprayed — 30 30 30 30 — — — on volatile componentsbeing transferred to the first condenser (kg/hr) Substance sprayed onvolatile — — — — — 4 5 — components being transferred to the secondcondenser Flow rate of substance sprayed — — — — — 30 30 — on volatilecomponents being transferred to the second condenser (kg/hr) Content ofvinyl cyanide monomer 13.9 14.2 14.5 16.6 17.0 19.5 19.5 55.3 which isnot condensed in the first condenser and is transferred to the secondcondenser (% by weight) Flow rate of volatile components 15.0 17.1 22.352.0 17.0 86.8 41.6 14.8 discharged without being condensed in thesecond condenser (kg/hr)

TABLE 5 Comparative Examples Classification 9 10 11 12 13 14 15 16Separation conditions in B B B C C C C C volatilization tankCondensation conditions in B B B C C C C C condenser Substance sprayedon volatile 2 4 — — 2 3 4 — components being transferred to the firstcondenser Flow rate of substance sprayed 30 30 — — 150 150 150 — onvolatile components being transferred to the first condenser (kg/hr)Substance sprayed on volatile — — 4 — — — — 5 components beingtransferred to the second condenser Flow rate of substance sprayed — —30 — — — — 110 on volatile components being transferred to the secondcondenser (kg/hr) Content of vinyl cyanide monomer 55.5 55.8 59.7 26.227.2 29.7 31.9 39.3 which is not condensed in the first condenser and istransferred to the second condenser (% by weight) Flow rate of volatilecomponents 15.4 21.0 51.3 58.0 59.9 80.5 177.8 129.7 discharged withoutbeing condensed in the second condenser (kg/hr)

As shown in Tables 1 to 5, in the case of Examples 1 to 21 according tothe present invention, the amount of the volatile components notcondensed in the second condenser and discharged therefrom isnegligible. Accordingly, wastewater treatment costs consumed in treatingthe discharged volatile components are not required. On the other hand,in the case of Comparative Examples 1, 8, and 12 according toconventional methods, the amount of the volatile components notcondensed in the second condenser is large, showing the flow rate of14.8 to 58.0 kg/hr.

In addition, in the case of Comparative Examples 2, 3, 9, 13, and 14, inwhich the aromatic vinyl monomer was sprayed into the first condenser,and in the case of Comparative Examples 4, 5, 10, and 15, in which thevinyl cyanide monomer was sprayed into the first condenser, the amountof the volatile components not condensed in the second condenser anddischarged therefrom was significantly increased. Accordingly, costsconsumed in treating the discharged volatile components may beincreased.

In addition, in the case of Comparative Examples 6, 7, 11, and 16, inwhich the vinyl cyanide monomer was sprayed into the second condenser,the amount of the volatile components not condensed in the secondcondenser and discharged therefrom was significantly increased.

The invention claimed is:
 1. A method of preparing an aromatic vinyl compound-vinyl cyanide compound polymer, comprising: separating volatile components from a polymerization product containing an aromatic vinyl compound-vinyl cyanide compound polymer, residual aromatic vinyl monomer, residual vinyl cyanide monomer, and an organic solvent using a volatilization tank; and condensing the separated volatile components using one condenser or two or more condensers connected in series, wherein the method comprises spraying an organic solvent onto the separated volatile components being transferred from the volatilization tank to the condenser; or spraying an organic solvent or an aromatic vinyl monomer onto the volatile components not being condensed in a first condenser and being transferred to a second condenser when the two or more condensers connected in series are used.
 2. The method according to claim 1, wherein the method comprises spraying the organic solvent onto the volatile components being transferred to the first condenser after being separated in the volatilization tank; and spraying the organic solvent or the aromatic vinyl monomer onto the volatile components not being condensed in the first condenser and being transferred to the second condenser.
 3. The method according to claim 1, wherein the separated volatile components comprise 5 to 35% by weight of a vinyl cyanide compound, 45 to 80% by weight of an aromatic vinyl compound, and 5 to 50% by weight of an organic solvent.
 4. The method according to claim 1, wherein, in the spraying of the organic solvent, the organic solvent is sprayed at a flow rate of 10 to 200 kg/hr.
 5. The method according to claim 1, wherein, in the spraying of the organic solvent, the organic solvent is sprayed at a temperature of −10 to 40° C.
 6. The method according to claim 1, wherein, in the spraying of the organic solvent or the aromatic vinyl monomer, the organic solvent or the aromatic vinyl monomer is sprayed at a flow rate of 10 to 220 kg/hr.
 7. The method according to claim 1, wherein, in the spraying of the organic solvent or the aromatic vinyl monomer onto the volatile components not being condensed in the first condenser and being transferred to the second condenser, the organic solvent or the aromatic vinyl monomer is sprayed at a temperature of −10 to 40° C.
 8. The method according to claim 1, wherein condensation in the first condenser is performed at a refrigerant temperature of 20 to 35° C. under an operating pressure of 3 to 100 Torr.
 9. The method according to claim 1, wherein condensation in the second condenser is performed at a refrigerant temperature of −3 to 4° C. under an operating pressure of 5 to 50 Torr.
 10. The method according to claim 1, wherein the separating is performed at a temperature of 220 to 260° C. under a pressure of 35 Torr or less.
 11. The method according to claim 1, wherein condensates condensed in the first and second condensers are recovered, purified, and reintroduced into a reactor.
 12. An apparatus for preparing an aromatic vinyl compound-vinyl cyanide compound polymer, comprising: a volatilization tank for separating volatile components from a polymerization product containing an aromatic vinyl compound-vinyl cyanide compound polymer, residual aromatic vinyl monomer, residual vinyl cyanide monomer, and an organic solvent; and one condenser or two or more condensers connected in series for condensing the separated volatile components, wherein the apparatus comprises a spray means for spraying an organic solvent into a transfer pipe for transferring the separated volatile components to the condenser; or a spray means for spraying an organic solvent or an aromatic vinyl monomer into a transfer pipe for transferring the volatile components, which have not been condensed in a first condenser, to a second condenser, when the two or more condensers connected in series are comprised.
 13. The apparatus according to claim 12, wherein the apparatus comprises a spray pipe for spraying the organic solvent into the transfer pipe for transferring the separated volatile components to the first condenser; and a spray pipe for spraying the organic solvent or the aromatic vinyl monomer into the transfer pipe for transferring the volatile components, which have not been condensed in the first condenser, to the second condenser. 